Process and device for perforating or cutting printed laminated composite materials

ABSTRACT

A process and device are disclosed for perforating and/or partially cutting printed laminated composite materials by means of laser beams from at least one laser arranged in a laser station. In order to minimize equipment costs, in particular for the control of the perforation and/or partial cutting processes, without having to renounce to an exact positioning of the perforations and/or partial cuts, a process is disclosed characterized by the following steps: the laminated composite material web is cut into individual blanks (1) according to the printed image and/or folding pattern; the blanks (1) are transported to the laser station; and the perforations or partial cuts are carried out in the stationary blank (1). Also disclosed are means for carrying out the process.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a process and a device for producingperforations and/or semi-cuts in printed multilayer composite materialby means of laser beams from at least one laser arranged in a laserstation.

Multilayer composite material is used in particular for packagingfoodstuffs in folding box packages. In this a base layer of cardboard,paperboard or paper and if applicable an aluminium foil layer arrangedon top of it is provided on both sides with a layer of polyethylene(PE), in order to provide the subsequent package with the necessarycharacteristics regarding impermeability, ability to keep out oxygen,protection of the contents from light etc. As such known packages areprimarily used for milk, juice or similar; as a rule these packagescontain a printed image comprising details concerning the content,manufacturer, advertising or similar.

As a rule, the multilayer composite material is produced as a sheetmaterial; the surface of the material which will later be on the outsideof the package is provided with the desired printed images andtransported on rollers or directed to further use. Folding box packagingmade from this material often comprises weakening lines in the basematerial and the exterior PE layer, for example to facilitate theinsertion of drinking straws into the package or else to enable theintrusion of pouring aids. Such weakening lines which are either made asperforations or as semi-cuts (weakening lines in one or several layer/sof the composite material/s) must therefore be positioned on thecomposite material depending on the printed image, so as to be"correctly" located in the subsequent package.

From EP 0 357 841 B1, it is already known to lead a sheet of compositematerial past a laser station, depending on the printed image, with thecontrol of the laser taking place depending on the previously scannedprinted image. It is quite evident that this process is extremelyexpensive because laser treatment has to be carried out while the sheetis moving. To this purpose the movement of the laser beam must not onlytake into account the actual contour of the notch but also the speed ofthe sheet.

From GB 21 61 427 A a process by itself for treating thermoplastic cutshapes e.g. PVC is already known, in which folding lines are made inthese cut shapes by means of a laser beam applied through a mask, inorder to fold a container for packaging purposes from this cut shape. Inthis it is however necessary to fix the PVC cut shapes ontonegative-pressure tables in order to treat the said cut shapes. Bycontrast, the process according to the invention does not require suchconstruction expenditure.

In addition, the production of cut shapes with smooth-cut edges fromsheets of paper, by the application of laser beams, has by itself alsobeen known for a long time (DE 32 22 394 A1). In addition, a laser beamhas already been used as a device for longitudinal separation of sheetmaterial on sheet processing machines, as is known from DE 26 14 941A1by itself.

It is thus the object of the present invention to further improve anddevelop a device of the type mentioned in the introduction in that theconstruction effort in particular regarding the control during theproduction of the perforation and/or the semi-cuts, is minimised withouthaving to renounce exact positioning of the perforations and/orsemi-cuts.

In a process of the type mentioned in the introduction, this object ismet by the following steps:

cutting the sheet of multilayer composite material into individual cutshapes, depending on the printed image and/or the fold pattern;

transporting the cut shapes to the laser station;

positioning and fixing the cut shapes laterally and in the plane oflaser treatment by means of limit-stop means; and

producing the perforation lines or semi-cut lines while the cut shape isstationary, depending on the limit-stops.

Regarding a device, the task is solved by providing a device for cuttingthe sheet of multilayer composite material into individual cut shapes, alaser station with at least one laser and respective deflector devicesfor guiding each laser beam as well as limit-stop means for positioningthe individual cut shapes fed to the laser station, in the plane oflaser treatment, and providing respective transport means and/orstacking means for the individual cut shapes.

According to the invention it is thus no longer the moving sheet ofmultilayer composite material which is subjected to laser treatment butthe said sheet is first cut into individual cut shapes which are thenlaser-treated and from which finally the actual packages are produced.Since printing of the composite material takes place mechanically andthus in good register, the sheet of composite material, too, is cut intocut shapes in good register, so that laser treatment is no longerundertaken depending on the printed image but rather can be undertakendepending on the edges of the cut shapes. In this way, the constructioneffort with the process according to the invention and the respectivedevice is clearly less than in the known process because elaboraterecognition of the printed image and complicated laser control systemdepending on the speed of the sheet can be done without.

According to a preferred embodiment of the invention, during lasertreatment the cut shapes to be treated are aligned in a horizontalplane. In this way, gravity is used to let the flat cut shapes rest inone plane so that no surface curvatures, throws or similar can result.

In this, the actual laser treatment of the stationary cut shapes can behandled according to three alternative options. A first embodiment ofthe invention provides for the individual cut shapes to be stacked priorto laser treatment; for laser treatment to take place on the topmost cutshape in the stack; and for the treated cut shapes to be drawn offindividually from the stack, step by step to one side. Alternatively itis however also possible for the individual cut shapes to be fed to thelaser station and stacked there; for laser treatment to take place onthe topmost cut shape in the stack; and for the stack forming below thelaser station to be moved downwards, step by step; or else for the cutshapes to undergo laser treatment individually, With the first and thirdvariant it is advantageous, in a further embodiment of the invention, tostack the finished cut shapes behind the laser station.

In this, selection of the optimal form of laser treatment depends firstof all on the space available and the operational requirements. Thus thefirst alternative suggests itself in particular in those cases where thecut shapes which have been previously separated, are already stacked,for example in order to be transported to the laser station. The secondalternative is always of advantage if the laser-treated cut shapes areto be stacked anyway. In this, depending on the operationalcircumstances, supply of the cut shapes to the laser station can takeplace directly or else by using one or several intermediary stackingmagazines, in order to separate the printing and cutting processes onthe one hand, from the laser treatment process on the other hand.

According to a further teaching of the invention, the intensity of thelaser beam or beams applied is adjustable. This is of great importancein particular for the production of semi-cuts since, depending on thedesign of the multilayer composite material, a different intensity oflocal evaporation in one or several layers of the material to be removedis required.

From the point of view of device design, the three alternative processestake place in such a manner that the limit-stop means for positioningand fixing the cut shapes to be treated are designed in such a way thatthe laser station comprises a chute through which a multiple number ofhorizontally stacked cut shapes are fed from below; or else that thelimit-stop means are designed in such a way that the individual cutshapes are laterally fed to the laser station and that below the laserstation a stacking magazine for the completely treated cut shapes isarranged. It is advantageous if according to a further teaching of theinvention, there is a stacking device behind the laser station, forholding the cut shapes upon completion of their treatment.

If the laser station is not to be equipped with a feed chute or removalchute for feeding or removing stacks of cut shapes, then in the deviceaccording to the third alternative, the limit-stop means are designed insuch a way that the individual cut shapes of the laser station are fedin and removed again in the treatment plane. For the cut shapes fed tothe laser station horizontally, it is advantageous if in front of thelaser station, means for stacking and singling out cut shapes arearranged in order to separate the above-mentioned procedures of printingand cutting on the one hand, and laser treatment on the other hand.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the three variants according to the invention are illustrated inmore detail by means of a drawing merely showing embodiments of theinvention, where:

FIG. 1 shows a first embodiment of a device according to the inventionin diagrammatic representation;

FIG. 2 shows a second embodiment of the device according to theinvention; and

FIG. 3 shows a third embodiment of the device according to theinvention.

DESCRIPTION OF THE INVENTION

In the drawing, identical components are represented by identicalreference characters. In the case of all three variants, cut shapes 1are provided with perforations and/or semi-cuts by at least one laserbeam of a laser 2, by way of deflector devices 3 shown diagrammaticallyonly. In all three Figs., the direction of movement of the cut shapes 1is in the direction of the arrows which are not further designated, i.e.from right to left.

In the first variant, shown in FIG. 1, feeding the cut shapes 1 takesplace from below, with the topmost cut shape 1 always being limited by aheight stop 4, in order to fix the cut shape 1 in the focal plane of thelaser 2. A chute guide 5, also shown in diagrammatic representationonly, ensures that the stack 6 previously made from cut shapes 1 is fedin such a way that the cut shapes 1 are horizontally surrounded withoutany play, by the side walls of the chute. In the embodiment shown inFIG. 1 which is the preferred embodiment, the cut shapes 1 aftercompletion of treatment by the laser 2 are fed to a stacker 7' and thereplaced in stacks 6'. In addition, FIG. 1 shows a further precedingstacker 7, shown in dot-dash outline, which after singling out the cutshapes 1 is used to produce stack 6 from where the cut shapes are thenfed to the actual laser station.

The device shown in FIG. 2 differs from that in FIG. 1 in that thefeeding of the cut shapes 1 takes place laterally in a horizontal planewith a lateral limit stop 8 ensuring that the cut shapes 1 to be treatedare fixed without any play. In this, stack formation of the cut shapes 1which have already undergone laser treatment takes place below thetreatment plane, by step-by-step lowering of the cut shapes which haveundergone treatment.

Finally, FIG. 3 shows a third variant of the device according to theinvention in which both feed-in to, and removal from, the laser station,of the cut shapes 1 occurs in the horizontal treatment plane. It isadvantageous if here too, the cut shapes 1 are stacked to stacks 6 in adownstream stack former 7; with the stacks portioned for subsequentfurther treatment. Here too, it can be advantageous to single outalready existing stacks 6' by a further stacker 7' preceding the laserstation, in order to attain separation of the preceding printing andcutting devices.

What is claimed is:
 1. A process for producing perforation lines and/orsemi-cut lines in printed multilayer composite material using laserbeams from at least one laser arranged in a laser station,comprising:cutting the sheet of multilayer composite material intoindividual cut shapes, depending on the printed image and/or foldpattern; transporting the cut shapes to the laser station; positioningand fixing the cut shapes laterally and in the plane of laser treatmentwith limit-stops; and producing the perforation lines or semi-cut lineswhile the cut shape is stationary, depending on the limit-stops.
 2. Aprocess according to claim 1, further comprising aligning the cut shapesto be treated in a horizontal plane.
 3. A process according to claim 1,further comprising stacking the individual cut shapes prior to lasertreatment, treating the topmost cut shape in the stack with the laser,and drawing the treated cut shapes off individually from the stack toone side.
 4. A process according to claim 1, further comprising movingpreviously treated cut shapes downward, feeding the individual cutshapes to the laser station, placing the cut shapes on top of thepreviously treated cut shapes to form a stack, and treating the topmostcut shape in the stack with the laser.
 5. A process according to claim1, wherein the cut shapes undergo laser treatment individually.
 6. Aprocess according to claim 3, further comprising conveying the stackupward step-by-step from below against a height stop whose lower edge isin the treatment plane of the laser.
 7. A process according to claim 3,further comprising stacking the treated cut shapes.
 8. A processaccording to claim 1, further comprising adjusting the intensity of thelaser beam.
 9. A device for producing perforation lines and/or semi-cutlines in printed multilayer composite material, comprising:a device forcutting a sheet of multilayer composite material into individual cutshapes; a laser station comprising:at least one laser; at least onedeflector device for guiding each laser beam; and at least onelimit-stop to position the individual cut shapes fed to the laserstation; a transport device; and optionally, a stacking device.
 10. Adevice according to claim 9, wherein the laser station is arranged abovethe horizontally arranged cut shapes to be treated on the printed side.11. A device according to claim 9, wherein the at least one limit stopcomprises a chute by which a multiple number of horizontally stacked cutshapes are fed from below.
 12. A device according to claim 9, whereinthe at least one limit stop is designed so that the individual cutshapes are laterally supplied to the laser station.
 13. A deviceaccording to claim 12, further comprising a stacking magazine locatedbelow the laser station to hold the treated cut shapes.
 14. A deviceaccording to claim 9, wherein the at least one limit stop is arranged sothat the individual cut shapes are fed to the laser station and removedin the treatment plane.
 15. A device according to claim 9, furthercomprising a stacking device for the treated cut shapes located afterthe laser station.
 16. A device according to claim 9, further comprisinga stacking device located ahead of the laser station.